All Packages  Class Hierarchy  This Package  Previous  Next  Index

Class javax.comm.CommPortIdentifier

java.lang.Object
   |
   +----javax.comm.CommPortIdentifier

public class CommPortIdentifier

extends Object

• Determining the communications ports made available by the driver.
• Opening communications ports for I/O operations.
• Determining port ownership.
• Resolving port ownership contention.
• Managing events that indicate changes in port ownership status.

An application first uses methods in CommPortIdentifier to negotiate with the driver to discover which communication ports are available and then select a port for opening. It then uses methods in other classes like CommPort, ParallelPort and SerialPort to communicate through the port.

See Also:

CommPort, CommPortOwnershipListener, ParallelPort, SerialPort

PORT_PARALLEL

IEEE 1284 parallel port

PORT_SERIAL

RS-232 serial port

addPortName(String, int, CommDriver)

Adds portName to the list of ports.

addPortOwnershipListener(CommPortOwnershipListener)

Registers an interested application so that it can receive notification of changes in port ownership.

getCurrentOwner()

Returns the owner of the port.

getName()

Returns the name of the port.

getPortIdentifier(CommPort)

Obtains the CommPortIdentifier object corresponding to a port that has already been opened by the application.

getPortIdentifier(String)

Obtains a CommPortIdentifier object by using a port name.

getPortIdentifiers()

Obtains an enumeration object that contains a CommPortIdentifier object for each port in the system.

getPortType()

Returns the port type.

isCurrentlyOwned()

Checks whether the port is owned.

open(FileDescriptor)

Opens the communications port using a FileDescriptor object on platforms that support this technique.

open(String, int)

Opens the communications port.

removePortOwnershipListener(CommPortOwnershipListener)

Deregisters a CommPortOwnershipListener registered using addPortOwnershipListener

 public static final int PORT_SERIAL

RS-232 serial port

 public static final int PORT_PARALLEL

IEEE 1284 parallel port

 public static Enumeration getPortIdentifiers()

Obtains an enumeration object that contains a CommPortIdentifier object for each port in the system.

Returns:

an Enumeration object that can be used to enumerate all the ports known to the system

See Also:

Enumeration

 public static CommPortIdentifier getPortIdentifier(String portName) throws NoSuchPortException

Obtains a CommPortIdentifier object by using a port name. The port name may have been stored in persistent storage by the application.

Parameters:

portName - name of the port to open

Returns:

a CommPortIdentifier object

Throws: NoSuchPortException

if the port does not exist

 public static CommPortIdentifier getPortIdentifier(CommPort port) throws NoSuchPortException

Obtains the CommPortIdentifier object corresponding to a port that has already been opened by the application.

Parameters:

port - a CommPort object obtained from a previous open

Returns:

a CommPortIdentifier object

Throws: NoSuchPortException

if the port object is invalid

 public static void addPortName(String portName,
                                int portType,
                                CommDriver driver)

Adds portName to the list of ports.

Parameters:

portName - The name of the port being added

portType - The type of the port being added

driver - The driver representing the port being added

See Also:

CommDriver

 public String getName()

Returns the name of the port. The port name should be identifiable by the user. Ideally, it should be the label on the hardware. For example, "COM1" and "COM2" on PCs; "Serial A" and "Serial B" on Sun Ultra workstations. The port name may be stored by an application and subsequently used to create a CommPortIdentifier object using getPortIdentifier(String portName) method.

Returns:

the name of the port

 public int getPortType()

Returns the port type.

Returns:

portType - PORT_SERIAL or PORT_PARALLEL

 public synchronized CommPort open(String appname,
                                   int timeout) throws PortInUseException

Opens the communications port. open obtains exclusive ownership of the port. If the port is owned by some other application, a PORT_OWNERSHIP_REQUESTED event is propagated using the CommPortOwnershipListener event mechanism. If the application that owns the port calls close during the event processing, then this open will succeed. There is one InputStream and one OutputStream associated with each port. After a port is opened with open, then all calls to getInputStream will return the same stream object until close is called.

Parameters:

appname - Name of application making this call. This name will become the owner of the port. Useful when resolving ownership contention.

timeout - time in milliseconds to block waiting for port open.

Returns:

a CommPort object

Throws: PortInUseException

if the port is in use by some other application that is not willing to relinquish ownership

 public String getCurrentOwner()

Returns the owner of the port.

Returns:

current owner of the port.

 public boolean isCurrentlyOwned()

Checks whether the port is owned.

Returns:

boolean true if the port is owned by some application, false if the port is not owned.

 public void addPortOwnershipListener(CommPortOwnershipListener listener)

Registers an interested application so that it can receive notification of changes in port ownership. This includes notification of the following events:

• PORT_OWNED: Port became owned
• PORT_UNOWNED: Port became unowned
• PORT_OWNERSHIP_REQUESTED: If the application owns this port and is willing to give up ownership, then it should call close now.

The ownershipChange method of the listener registered using addPortOwnershipListener will be called with one of the above events.

Parameters:

listener - a CommPortOwnershipListener callback object

 public void removePortOwnershipListener(CommPortOwnershipListener lsnr)

Deregisters a CommPortOwnershipListener registered using addPortOwnershipListener

Parameters:

listener - The CommPortOwnershipListener object that was previously registered using addPortOwnershipListener

 public CommPort open(FileDescriptor fd) throws UnsupportedCommOperationException

Opens the communications port using a FileDescriptor object on platforms that support this technique.

Parameters:

fd - The FileDescriptor object used to build a CommPort.

Returns:

a CommPort object.

Throws: UnsupportedCommOperationException

is thrown on platforms which do not support this functionality.

All Packages  Class Hierarchy  This Package  Previous  Next  Index